change picture each time web page loads

Image can change on web page, you know...like showing different christmas pictures when web page loads on a users computer. I want them to see a different picture each time in php page.


$file=array();

$file[0]="file1.gif";
$file[1]="file2.gif";
$file[2]="file3.gif";
$file[3]="file4.gif";
$file[4]="file5.gif";
$file[5]="file6.gif";
$file[6]="file7.gif";
$file[7]="file8.gif";

$fileno=rand(0,7);

$filename=$file[$fileno];

echo '<img src="$filename" >';

?>